In general, a midplane is a circuit board which connects to other circuit boards on each side. Midplanes are often used in data storage systems where one side of the chassis accepts processing cards (e.g., storage processors) and the other side of the chassis accepts other types of cards such as I/O cards, service modules and power supplies. Midplanes are suitable for use in other types of systems as well such as networking systems.
One conventional computerized system has a midplane which is vertically oriented within its enclosure which accommodates horizontal airflow. Horizontally oriented processing boards insert through one side of the enclosure and connect to one side of the midplane. Vertically oriented disk drives insert through the other side of the enclosure and connect to the other side of the midplane. The midplane defines a series of narrow air slots which enable air to pass between the processing board side of the midplane and the disk drive side of the midplane for cooling purposes. Elongated disk drive connectors are interleaved between the narrow air slots to enable the disk drives to electrically connect to the midplane without blocking the narrow air slots.
Other conventional computerized systems have midplanes which are oriented so that the midplanes do not fully extend (i.e., from the top to the bottom, and from side to side) within horizontal airflow enclosures (e.g., a midplane can lay flat on the bottom of the enclosure). In such a configuration, air is allowed to flow around the midplane (e.g., from the front of the enclosure over the midplane to the back).